1. Technical Field
This disclosure relates to continuous and batch manufacture of polymer emulsions such as HIPE and to use of electrical or wave energy in the RF range during the cell forming process or in physical after-treatment of a cellular product. It also relates to polycomposite polymer foams (such as, for example, carbon nanotubes in styrene or ABS monomer becoming a nanocomposite upon polymerization) and to methods of improving the strength and conductivity of polycomposite foams by linking conductive particles included therein (such as, for example, carbon nanotubes in styrene or ABS polymer) into nanostructure which increases bulk conductivity.
2. Discussion of the Related Art
High Internal Phase Emulsion (HIPE) foam is made from a polymer emulsion comprising immiscible phases: a continuous phase and an internal phase. The continuous phase is also called the oil phase and the internal phase is also called the aqueous phase, although non-aqueous emulsions comprising immiscible organic compounds are included in this definition.
Curing of an emulsion to produce a stable and solid foam is conventionally done by baking the foam in a curing chamber. Low polymer thermal conductivity frustrates heating the interior of the foam from the outside. Alternatively, ultraviolet (UV) treatment is used. For an excellent review of the field of UV and conventional heat treatment of HIPE foam containing polyelectrolytes, see Clear, et al. U.S. Pat. No. 6,890,963 (2005). RF curing of sponge rubber is disclosed in Bosomworth, et al. U.S. Pat. No. 2,604,665 (1952).
An unsolved problem in the art of HIPE manufacture is the auto-acceleration effect, where localized heat buildup during polymerization causes polymers to ball up and conceal their evolving active ends, which impedes complete monomer-to-polymer conversion and crosslinking of polymers. However, crosslinking of polymers is desirable for durability and stretchability.
Nanocomposite polymer foams, comprising carbon nanotubes, are known to have advantageous properties, such as light weight, conductivity and durability. They offer promise as replacements for conventional conductive materials, such as copper wire. However, carbon nanotubes produced by conventional methods are undesirably short.
Accordingly, a need remains for a process of forming a foam material that avoids the auto-acceleration effect. A need also remains for a process of forming a nanocomposite polymer foam having macroscale nanostructures formed from carbon nanotubes.